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fixed calibration

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miguel5612
2019-05-29 20:58:22 -05:00
parent 1924e21e61
commit 6d1229977e
2 changed files with 28 additions and 10 deletions
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15
src/MQUnifiedsensor.cpp
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@@ -136,12 +136,25 @@ int MQUnifiedsensor::readPPM(int m, int b) {
return floor(ppm); return floor(ppm);
} }
double MQUnifiedsensor::calibrate() { double MQUnifiedsensor::calibrate() {
//More explained in: https://jayconsystems.com/blog/understanding-a-gas-sensor
/*
V = I x R
VRL = [VC / (RS + RL)] x RL
VRL = (VC x RL) / (RS + RL)
Así que ahora resolvemos para RS:
VRL x (RS + RL) = VC x RL
(VRL x RS) + (VRL x RL) = VC x RL
(VRL x RS) = (VC x RL) - (VRL x RL)
RS = [(VC x RL) - (VRL x RL)] / VRL
RS = [(VC x RL) / VRL] - RL
*/
float sensor_volt; //Define variable for sensor voltage float sensor_volt; //Define variable for sensor voltage
float RS_air; //Define variable for sensor resistance float RS_air; //Define variable for sensor resistance
float R0; //Define variable for R0 float R0; //Define variable for R0
float sensorValue; //Define variable for analog readings float sensorValue; //Define variable for analog readings
sensor_volt = this->getVoltage(); //Convert average to voltage sensor_volt = this->getVoltage(); //Convert average to voltage
R0 = sensor_volt / _ratioInCleanAir; //Calculate R0 RS_air = ((VOLT_RESOLUTION*RLValue)/sensor_volt)-RLValue; //Calculate RS in fresh air
R0 = RS_air/_ratioInCleanAir; //Calculate R0
return R0; return R0;
} }
double MQUnifiedsensor::getVoltage() { double MQUnifiedsensor::getVoltage() {

11
src/MQUnifiedsensor.h
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@@ -4,9 +4,16 @@
#include <Arduino.h> #include <Arduino.h>
#include <stdint.h> #include <stdint.h>
//Count of posible lectures //Count of posible lectures
#define lecturesAvailable 19 #define lecturesAvailable 19
/************************Global vars************************************/
int VOLT_RESOLUTION = 5.0; // if 3.3v use 3.3
int RLValue = 10; //Value in KiloOhms
int _ratioInCleanAir, _PPM;
double RS_air,_R0, _m, _b, _ratio;
/************************Hardware Related Macros************************************/ /************************Hardware Related Macros************************************/
//Index in the nameLecture vector //Index in the nameLecture vector
@@ -82,10 +89,8 @@ class MQUnifiedsensor
private: private:
int _pin, _type, _PPM, _lecturePosInArray, _ratioInCleanAir; int _pin, _type;
double RS_air,_R0 = 11.820, _m, _b, _ratio;
String _MQ[19], _nameLectureRequeired; String _MQ[19], _nameLectureRequeired;
int VOLT_RESOLUTION = 5.0; // if 3.3v use 3.3
}; };
#endif //MQUnifiedsensor_H #endif //MQUnifiedsensor_H